1. Field of the Invention
The present invention relates to an image formation apparatus such as a digital copy machine that can selectively execute an image formation process of a host mode to form an image on a sheet according to image data applied from a specific image input device and an image formation process of a guest mode to form an image on a sheet according to image data applied from a device other than the specific image input device.
2. Description of the Background Art
In an image formation apparatus that forms an image on a sheet according to image data applied from an image input device, the image formation process is carried out by a host mode according to image data applied from a specific image input device arranged inside or in the proximity of the image formation apparatus, as well as by a guest mode according to image data applied from an external image input device connected through a data transmission line.
For example, in a digital copy machine including the facsimile function, a facsimile mode process is executed to form on a sheet an image transmitted from an external facsimile apparatus via a public switched telephone network, in addition to the copy mode process of copying on a sheet an image of an original document read out by an internal image reader. Some other multi-function digital copy machines receive an image input produced by an external personal computer or read out by a scanner to execute a print mode process of forming the input image on a sheet.
In the above multi-function digital copy machine, the sheet on which an image is to be formed must be provided reliably in executing the process of each mode. In the host mode, the operator can confirm the presence of a sheet in the sheet feed unit of the digital copy machine in the copy mode process to replenish the sheet feed unit with sheets when in the case of shortage. In the process of the facsimile mode or a printer mode corresponding to the guest mode, there are cases where the operator of the external device such as the facsimile apparatus or personal computer cannot confirm the presence/absence of the sheet in the sheet feed unit.
In the case where the sheet required for execution of the guest mode process is not accommodated in the sheet feed unit of the digital copy machine, the required sheet may not be promptly supplied. The process will be deferred. Particularly in the case where the same sheet feed unit is shared by a plurality of mode processes, the remaining number of sheets in the sheet feed unit may often be insufficient at the initiation of the guest mode process due to the usage of many sheets in the host mode process.
A copy machine with a facsimile function disclosed in Japanese Patent Laying-Open No. 7-250190 has a structure in which at least one sheet cassette out of a plurality of sheet feed trays (referred to as xe2x80x9ccassettexe2x80x9d appropriately hereinafter) can be set as the cassette directed to facsimile recording. Sheets are supplied from different sheet cassettes between the copy mode process and the facsimile mode process. This ensures the provision of sheets to be used in a facsimile mode process from the dedicated sheet cassette even when a great number of sheets are used in the copy mode process.
However, it will become necessary to mount a plurality of sheet cassettes each accommodating sheets of various sizes for each mode at the sheet feed unit if a sheet cassette accommodating the sheets to be used in the facsimile mode process corresponding to the guest mode is provided in addition to the sheet cassette accommodating the sheets to be used in the copy mode process corresponding to the host mode as in the above apparatus of Japanese Patent Laying-Open No. 7-250190. There was a problem that the entire size of the apparatus is increased.
Also, it is to be noted that the ratio of the accommodated number of sheets that can be used for the copy mode process of high usability to the total number of accommodated sheets in the sheet feed unit is reduced. As a result, the sheets remaining in the sheet cassette set exclusively for the facsimile mode will not be able to be used for the copy mode process even if the number of sheets to be used in the facsimile mode process is significantly lower than the number of sheets to be used in the copy mode process. There was a disadvantage that the frequency of sheet replenishment is increased to render the task of the copy mode process tedious.
In the host mode process, the sheet cassette dedicated to the host mode can be easily replenished since the operator is usually present in the proximity of the apparatus. However, in the guest mode process where the operator is not present in the proximity of the apparatus, the sheets cannot be promptly supplied for replenishment when the accommodated number of sheets in the sheet cassette dedicated to the guest mode becomes low after repetitive execution of the guest mode process or the usage of a large amount of sheets in the previous guest mode process. There is a possibility that the succeeding guest mode process cannot be executed.
The above problems are encountered, not only in the multi-function type digital copy machine, but also in printers connected to a particular personal computer or to an external facsimile apparatus or another personal computer that is connected to a public switched telephone network.
An object of the present invention is to provide an image formation apparatus that can ensure provision of sheets to be used in a host mode process and a guest mode process without increasing the number of sheet cassettes mounted at the sheet feed unit, and that does not have the process task rendered complicated as a result of frequent sheet supply by switching the state of the sheet cassette dedicated to the guest mode with respect to the accommodated number of sheets in the sheet cassette.
According to an aspect of the present invention, an image formation apparatus selectively executes an image formation process of either a host mode according to image data input from a particular device or a guest mode according to image data input from a device other than the particular device with respect to the sheet accommodated at the sheet feed position.
In the present image formation apparatus, the guest mode dedicated set state of using the sheet accommodated at the sheet feed position only for the image formation process of the guest mode can be altered according to the result of comparing the accommodated number of sheets at the sheet feed position and the number of sheets to be ensured for provision in the guest mode.
In the present invention, the set state dedicated to the guest mode as to the sheet feed position is altered according to the result of comparing the accommodated number of sheets at the sheet feed position with the number of sheets to be ensured for provision in the guest mode. Therefore, the sheet feed position dedicated to the guest mode is not fixedly set. The sheets accommodated at the sheet feed position can be used efficiently in the image formation processes of both the host mode and the guest mode according to the usage state of the sheet.
When the accommodated number of sheets at a unitary or plurality of sheet feed positions becomes as low as a set value of the number of sheets to be ensured for provision as to the guest mode in the image formation apparatus of the present aspect, that sheet feed position is set as the sheet feed position dedicated to the guest mode.
When sheets are used in the image formation process of the host mode or the guest mode in the image formation apparatus of the present aspect so that the accommodated number of sheets at the sheet feed position becomes as low as the set number of sheets to be ensured for provision in the image formation process of the guest mode, that sheet feed position is set as the sheet feed position dedicated to the guest mode. Therefore, a plurality of sheets corresponding to the set number of sheets to be ensured for provision in the guest mode image formation process subtracted from the initial number of accommodated sheets at the sheet feed position is to be used for the image formation process of the host mode and the guest mode. The set number of sheets to be ensured for provision in the guest mode image formation process is used only for the image formation process of the guest mode. Therefore, provision of a sufficient number of sheet can always be ensured for the image formation process of the guest mode in which the operator generally cannot easily replenish the supply unit with sheets.
Preferably in the image formation apparatus, the setting of the sheet feed position dedicated to the guest mode can be switched to another sheet feed position when the accommodated number of sheets at the sheet feed position set exclusively for the guest mode among the unitary or plurality of sheet feed positions become as low as the set number of sheets to be ensured for provision in the guest mode image formation process.
When the accommodated number of sheets at the sheet feed position dedicated to the guest mode is used in the guest mode image formation process to become as low as the set number of sheets, the remaining sheets are used only for the host mode image formation process, and another sheet feed position is set as the sheet feed position dedicated to the guest mode. Therefore, the sheet feed position reduced in the accommodated number of sheets is to be used for the host mode image formation process in which sheet replenishment can be carried out readily, and the sheet feed position where more sheets are accommodated is to be used for the guest mode image formation process in which sheet replenishment cannot be carried out readily.
Preferably in the image formation apparatus, the set number of sheets to be ensured for provision in the guest mode image formation process can be set variable according to the time zone.
In the present image formation apparatus, the setting for the guest mode as to the sheet feed position is altered on the basis of a different set value of the number of sheets according to the time zone. Therefore, even in the case where the number of sheets used in the guest mode image formation process changes according to the time zone, the sheets accommodated at the sheet feed position are to be used in the host mode image formation process within the constantly ensured range of a sufficient number of sheets for the guest mode image formation process whatever time zone it may be.
In the image formation apparatus, the set number of sheets to be ensured for provision in the guest mode image formation process is preferably variable according to the day of a week such as a weekday or a weekend day.
In the image formation apparatus, the setting dedicated to the guest mode as to the sheet feed position can be altered on the basis of a different set value of the number of sheets according to the day of the week. Therefore, even in the case where the number of sheets used for the guest mode image formation process differs according to the day of the week, the sheets accommodated at the sheet feed position can be used for the host mode image formation process within the range of a sufficient number of sheets always ensured for the guest mode image formation process whatever day of the week it may be.
Prior to initiation of a host mode image formation process, the number of sheets to be used in the host mode image formation process is subtracted from the accommodated number of sheets at the sheet feed position, and sheet replenishment for a sheet feed position is designated according to the result of comparison between the subtracted value and the set value of the number of sheets to be ensured for provision in the guest mode image formation process.
Prior to initiation of a host mode image formation process, determination is made whether the accommodated number of sheets after execution of the host mode image formation process will become lower than the set number of sheets to be ensured for provision in the guest mode image formation process. Designation is made to carry out sheet replenishment according to the determination result. Therefore, in the case where the accommodated number of sheets will become lower than the number of sheets set to be ensured for the guest mode image formation process if the host mode image formation process is executed, sheets can be reliably supplied for replenishment prior to initiation of the host mode image formation process. A sufficient number of sheets can be ensured for provision as to the guest mode image formation process.